diff --git a/autospec/specfiles.py b/autospec/specfiles.py
index 4e9c0bd..0e2bd9d 100644
--- a/autospec/specfiles.py
+++ b/autospec/specfiles.py
@@ -402,10 +402,10 @@ class Specfile(object):
     def write_32bit_exports(self):
         """Write 32bit only env exports."""
         self._write_strip('export PKG_CONFIG_PATH="/usr/lib32/pkgconfig"')
-        self._write_strip('export ASFLAGS="$ASFLAGS --32"')
-        self._write_strip('export CFLAGS="$CFLAGS -m32"')
-        self._write_strip('export CXXFLAGS="$CXXFLAGS -m32"')
-        self._write_strip('export LDFLAGS="$LDFLAGS -m32"')
+        self._write_strip('export ASFLAGS="${ASFLAGS}${ASFLAGS:+ }--32"')
+        self._write_strip('export CFLAGS="${CFLAGS}${CFLAGS:+ }-m32"')
+        self._write_strip('export CXXFLAGS="${CXXFLAGS}${CXXFLAGS:+ }-m32"')
+        self._write_strip('export LDFLAGS="${LDFLAGS}${LDFLAGS:+ }-m32"')
 
     def write_variables(self):
         """Write variable exports to spec file."""